A short-video app is an app that shows a feed of clips a few seconds to a minute long, made by its users, ranked to keep each viewer watching, and paid for by ads between the clips. The viewer swipes up to see the next clip. There is no need to search or choose. The app chooses for the viewer.
In India, short-video apps grew quickly after the government banned TikTok and other Chinese apps in June 2020. Several Indian apps took over its users, many of them in small towns and in Indian languages.
The most important software in the app is the ranking. Here is a typical case. A college student in Guwahati posts a 20-second dance clip with an Assamese song. The app first shows it to about 200 viewers who like dance clips in Assamese. For each viewer, it records whether they watched to the end, watched it twice, liked it, shared it or swiped away within two seconds. If most of the 200 watch to the end, the app shows the clip to 2,000 more viewers, then to 20,000. If most swipe away, the clip stops spreading. This kind of ranking is explained in recommendation systems. Watch time matters most, because the app earns more when viewers stay longer.
The clip also has to reach each phone quickly. When the student uploads it, the app converts it into several versions, from low quality to high quality. On a weak mobile network, the viewer's phone plays the low-quality version, so the clip does not stop to load. This is called adaptive bitrate streaming. Copies of popular clips are kept on a content delivery network (CDN), on servers close to viewers.
The app earns mainly from ads. After every few clips, the viewer sees an ad that looks like a clip. An advertiser's demand-side platform (DSP) bids for that space. Brands also pay popular creators to make clips about their products. Their marketing teams publish and track these posts through social media management tools.
Short-video apps must also remove harmful clips quickly. Software screens each new upload. Viewers can report a clip, and the reports go to trust and safety investigation. As in any social app, a person reviews the harder decisions.
How is it different from a streaming service (OTT)? A streaming service shows films and series made by studios, and the viewer chooses what to watch. A short-video app shows clips made by users, and the app chooses the next one.